This invention relates generally to membrane plates, and, more particularly, to a membrane plate for attaching a membrane to a roof.
A roofing system generally includes a roof deck which is considered the structural supporting surface of a building extending between the surrounding exterior walls of the building.
The roof deck may be constructed from plywood, metal decking or concrete or any other suitable material. Depending upon the construction, the roof deck may extend over the surrounding exterior walls or the roof deck may stop short of the exterior walls thereby forming a parapet wall, i.e., a low retaining wall at the edge of the roof deck. If desired, the roofing system may also include an insulation barrier formed from any suitable material applied over the roof deck.
To make the roof deck and building weather resistant, a single-ply membrane roof is typically installed over the roof deck. The single ply membrane roof refers to a water impermeable single sheet of polymeric material such as ethylene propylene diene rubber (EPDM) having an adhesive thereon. The membrane roof has heretofore been installed on the roof deck using a variety of different methods.
For example, the interior of the membrane roof may be held to the roof deck by the use of ballast and/or penetrating or non-penetrating fastener means as known in the art. An example of a penetrating fastener means for retaining the membrane roof installed to a roof deck is by utilizing membrane plates in the form of a plurality of small, circular metal plates having a hole in the center and a roofing screw or other suitable fastener. In order to anchor the membrane roof, the membrane plates are spaced apart in rows on the membrane roof and the fastener is driven through the hole in each plate, the membrane roof, any insulation material, and then into the roof deck. The metal plates are covered by overlapping roof membrane and joined together with an adhesive. Other stress plates used in the past include long, straight bars with holes in the bar. In the past, most adhesives have been painted on.
During the course of assembly of the components, air is trapped on top of the plate and prevented from escape by virtue of the aggressive tack of the adhesive. Once the adhesive contacts another material, it bonds securely. Repositioning by breaking the adhesive or lifting the upper membrane to allow air to escape is virtually impossible. The resulting air bubble is trapped. Over time (months or years), the expansion and contraction of the bubble will compromise the sealing ability of the seam.
It is well known for a stress plate to be formed in a circular shape. For example, U.S. Pat. No. 4,787,188 (Murphy) teaches a circular stress plate. The stress plate taught by Murphy has an outer circular rib and an inner circular rib as well as a plurality of hinged prongs. The hinged prongs are disposed at equal radial distances from the center of the stress plate and circumferentially spaced apart from each other at angles of ninety degrees.
U.S. Pat. No. 6,004,645 (Hubbard) teaches a method of applying a roof membrane assembly to a roof deck with overlapping membranes utilizing an adhesive and fasteners. No provision is made for release of air bubbles.
U.S. Pat. No. 4,282,050 (Thiis-Evensen) teaches a stress plate for cladding a roof on a support structure. The fastening process taught includes applying an insulation layer on the support structure and applying edge abutting webs of cladding material over the insulation layer. The insulation layer and the cladding layers are simultaneously mechanically anchored to the support structure using fasteners. The edges of the webs and the fasteners are sealed by welding strips. The fastener taught by Thiis-Evensen for fastening the layers to the support structure is rectangular in shape with gripping claws disposed at each end of the plate.
U.S. Pat. No. 4,543,763 (Ernst) teaches a fastening plate having circumferentially spaced apart projections disposed on the plate. The plates taught by Ernst can be round or square and are adapted to control the rate of axial penetration of an anchor in masonry structure.